Distribution and abundance of calanoid copepods in the York River Estuary, Virginia, 1968 and 1969

Calanoid copepods were sampled quantitatively at twelve stations in the York River estuary monthly over a two year period. Twenty-two different calanoid species were identified, with five species, Acartia tonsa, A. clausi, Eurytemora affinis, Pseudocalanus minutus and Pseudodiaptomus coronatus making up 95% of the numbers present. Several factors were investigated to determine their biological influence was the ctenophore, Mnemiopsis leidyi, a predator which reduced copepod numbers logarithmically at stations at which it occurred. Increased river flow was followed by large increases in copepod numbers and was the most important physical influence. Distribution of all calanoid species appearing in the estuary was described. Seasonal copepod abundance and the Acartia tonsa - A. clausi distribution in other North American East Coast and Gulf of Mexico estuaries was compared with that of the York River